Bone Remodeling in Distraction Osteogenesis and Autogenous Onlay Graft Procedures used for Implant Placement in the Canine Model: Osteoblasts

Objective: To test whether onlay grafting versus distraction osteogenesis provides more stable bone for implant placement after alveolar ridge height augmentation procedures. Methods: A foxhound model was utilized in which five dogs had an onlay graft on one side of the mandible, and distraction osteogenesis on the other side after initial surgery to reduce ridge height. Healed socket sites after removal of third molars served as control sites. After the consolidation period for distraction was complete, implants were placed in the new bone and left in situ for 3 months. The mandibles were then resected and the new bone sites removed from the surrounding jaw tissue. The bone specimens were fixed, decalcified, processed for paraffin embedding, cut into 6µm sections and stained using Attwood?s stain. Sections were digitized at 10X magnification. Linear distances of total bone surface and bone surface covered with osteoblasts/ osteoid were measured using Metamorph software. The experimental observer was blinded to the experimental conditions to ensure impartiality. Results: The mean total remodeling surface of distraction osteogenesis bone (9.8 ± 0.04 µm) was 1.5 X and for onlay-grafted bone (17.8 µm) was 3.0 X that of control bone (6.3 µm). Total surface of distraction osteogenesis bone covered by osteoblasts or osteoid (5.2 ± 1.4 µm) was 0.5 X and that of onlay bone (17.8 µm) was 3.0 X that for control bone (6.3 µm). Discussion and Conclusion: Both distraction bone and onlay bone have greater remodeling surface areas than control bone. However, distraction bone has only half its surface area being actively remodeled while onlay and control bone have all their surface area being remodeled. This may indicate that distraction bone has reached a steady state of remodeling, while control and onlay bone is actively being remodeled. Supported by the Baylor Oral Health Foundation and NIH/NIDCR DE07188.